The purpose of this research study is to examine differences that exist between groups with and without premenstrual syndrome (PMS) in blood pressure, heart activity and hormonal responses at rest and in response to psychological and physical challenges. Furthermore, group comparisons of the degree to which sympathetic nervous system receptors contribute to blood pressure and heart activity, and how these relate to pain sensitivity will be made. Sympathetic nervous system involvement will be assessed by comparing responses after a drug (isproterenal) has been administered which enhances the activation of these receptors.